Biomaterial Database

Node-like axonal specializations along demyelinated central nerve fibres: ultrastructural observations. 1983

W F Blakemore, and K J Smith

Ultrastructural examination of long-term (1 month to 1 year) demyelinated axons of the central nervous system (CNS) has revealed the presence of certain features typical of nerve fibres at the node of Ranvier. Focal regions of dense undercoating of the axolemma were observed and these always extended along regions which were intimately associated with the processes of glial cells. In many cases the glial cells were astrocytes, but in some cases the cells resembled Schwann cells. The astrocytic and Schwann cell processes were sometimes finger-like and they thus resembled the normal projections of these cells onto the nodal axolemma of central and peripheral nerve fibres, respectively. Since the undercoated regions which were associated with astrocytic processes were also often remote from any oligodendrocyte or Schwann cell processes, it seems that certain node-like specializations may form or be sustained in the absence of myelin-forming cells.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009412	Nerve Fibers	Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.	Cerebellar Mossy Fibers,Mossy Fibers, Cerebellar,Cerebellar Mossy Fiber,Mossy Fiber, Cerebellar,Nerve Fiber
D011901	Ranvier's Nodes	Regularly spaced gaps in the myelin sheaths of peripheral axons. Ranvier's nodes allow saltatory conduction, that is, jumping of impulses from node to node, which is faster and more energetically favorable than continuous conduction.	Nodes of Ranvier,Nodes, Ranvier's,Ranvier Nodes,Ranviers Nodes
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003711	Demyelinating Diseases	Diseases characterized by loss or dysfunction of myelin in the central or peripheral nervous system.	Clinically Isolated CNS Demyelinating Syndrome,Clinically Isolated Syndrome, CNS Demyelinating,Demyelinating Disorders,Demyelination,Demyelinating Disease,Demyelinating Disorder,Demyelinations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001253	Astrocytes	A class of large neuroglial (macroglial) cells in the central nervous system - the largest and most numerous neuroglial cells in the brain and spinal cord. Astrocytes (from "star" cells) are irregularly shaped with many long processes, including those with "end feet" which form the glial (limiting) membrane and directly and indirectly contribute to the BLOOD-BRAIN BARRIER. They regulate the extracellular ionic and chemical environment, and "reactive astrocytes" (along with MICROGLIA) respond to injury.	Astroglia,Astroglia Cells,Astroglial Cells,Astrocyte,Astroglia Cell,Astroglial Cell,Astroglias,Cell, Astroglia,Cell, Astroglial
D001369	Axons	Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.	Axon
D012583	Schwann Cells	Neuroglial cells of the peripheral nervous system which form the insulating myelin sheaths of peripheral axons.	Schwann Cell,Cell, Schwann,Cells, Schwann
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor